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Mysql存儲二進制對象數據問題

時間：2023-03-15來源：系統城裝機大師作者：佚名

Mysql存儲二進制對象數據

首先數據庫存儲一個Object對象

需要在數據庫表中定義一個blob類型的字段

與數據庫對應的實體類

編寫一個操作二進制的工具類

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76 import java.io.*;

/**
* byte[]類型操作類
*/
public class BlobUtil {

/**
* 把object對象序列化為二進制字節數組
* @param object
* @return
*/
public static byte[] setObject(Object object) {
ByteArrayOutputStream baos = null;
ObjectOutputStream out = null;
try {
baos = new ByteArrayOutputStream();
out = new ObjectOutputStream(baos);
out.writeObject(object);
} catch (Exception e) {
e.printStackTrace();
} finally {
if (out != null) {
try {
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (baos != null) {
try {
baos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return baos.toByteArray();
}

/**
* 把二進制字節數組反序列化為object對象
* object當中的每個javaBean對象都必須實現序列化
* 最外層的類必須生成一個序列化ID
* @param bytes
* @return
*/
public static Object getObject(byte[] bytes) {
Object obj = null;
ByteArrayInputStream bais = null;
ObjectInputStream in = null;
try {
bais = new ByteArrayInputStream(bytes);
in = new ObjectInputStream(bais);
obj = in.readObject();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (bais != null) {
try {
bais.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return obj;
}
}

需要轉換為byte[]的對象必須實現序列化和生成一個序列化ID，生成一個序列化ID是為了解決類當中一但有修改，反序列化時序列化ID就會對應不上，如下圖：

類中如果有其他類為變量也需要實現序列化，否則從數據庫中取出數據然后反序列化成Object對象的時候會直接報錯

對user的數據進行操作

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41 import java.io.Serializable;

/**
* @author
* @description
* @date
*/
public class UserVO implements Serializable {

private static final long serialVersionUID = 1L;

private String userId;

private String userName;

private String password;

public String getUserId() {
return userId;
}

public void setUserId(String userId) {
this.userId = userId;
}

public String getUserName() {
return userName;
}

public void setUserName(String userName) {
this.userName = userName;
}

public String getPassword() {
return password;
}

public void setPassword(String password) {
this.password = password;
}
}

調用二進制工具類來轉換數據然后進行存取就可以了。

測試功能

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12 public class TestMain {

public static void main(String[] args) {
UserVO user = new UserVO();
user.setUserId("123456");
user.setUserName("張三");
byte[] dataValue = BlobUtil.setObject(user);
System.out.println("=====對象轉換成blob類型數據====="+Arrays.toString(dataValue));
UserVO userVO = (UserVO) BlobUtil.getObject(dataValue);
System.out.println("=====blob類型數據轉換成對象====="+ JSONObject.toJSONString(userVO));
}
}

打印輸出

=====對象轉換成blob類型數據=====[-84, -19, 0, 5, 115, 114, 0, 53, 99, 111, 109, 46, 100, 111, 108, 112, 104, 105, 110, 46, 109, 111, 100, 117, 108, 101, 115, 46, 116, 109, 115, 46, 100, 111, 109, 97, 105, 110, 46, 99, 117, 115, 116, 111, 109, 101, 114, 115, 101, 114, 118, 105, 99, 101, 46, 85, 115, 101, 114, 86, 79, 0, 0, 0, 0, 0, 0, 0, 1, 2, 0, 3, 76, 0, 8, 112, 97, 115, 115, 119, 111, 114, 100, 116, 0, 18, 76, 106, 97, 118, 97, 47, 108, 97, 110, 103, 47, 83, 116, 114, 105, 110, 103, 59, 76, 0, 6, 117, 115, 101, 114, 73, 100, 113, 0, 126, 0, 1, 76, 0, 8, 117, 115, 101, 114, 78, 97, 109, 101, 113, 0, 126, 0, 1, 120, 112, 112, 116, 0, 6, 49, 50, 51, 52, 53, 54, 116, 0, 6, -27, -68, -96, -28, -72, -119]
=====blob類型數據轉換成對象====={"userId":"123456","userName":"張三"}